The Magic of Indoor Seed Starting

Many gardeners would prefer to buy their transplants from a greenhouse or garden center, but if you are looking for some of the more exotic flowers or vegetables, you may have to start them indoors yourself.  Our local sources for transplants just can’t carry enough of a variety to please the more adventurous.  This summer I’m trying a green eggplant (Applegreen), an Ancho hot pepper, Ultima Morpho pansies, San Marzano tomatoes, and an old favorite, Passport cantaloupe and I haven’t seen any of these available locally.  Some of us just like to start our own seeds whenever possible and some will start plants that could be direct-seeded into gardens or flower beds just to get a jump on the growing season. Here are some basics, no matter which category you fall into.

First – when do you start plants indoors?  Most seed packets for tender plants will specify the time to transplant.  If not some general times are: eggplant – 12 weeks; peppers – 12 weeks; tomatoes – 7 weeks; melons – 6 weeks; Petunias – 10 weeks.  Count back that far from your anticipated transplanting time to figure out when to start them.  For example, now would be a good time to start your tomatoes. It is better to start them a little bit later than a little bit earlier.

Second – what do you use for seed starting?  Use soil-less starting mix.  This is a mixture of about two parts peat moss, one part perlite, and one part vermiculite.  It may include fertilizer and other materials to help it retain water.  Do not use potting soil as it is too heavy for seedlings and they will not get adequate oxygen down to their roots.  Whatever you do, do NOT use unpasteurized garden soil or compost as you very likely will be introducing your delicate seedlings to all sorts of undesirable organisms.  The containers you use can be all sorts of things.  You can spend a fortune on specialized Styrofoam planting cells with trays that automatically wick moisture to the planting medium or you can build a shallow tray out of scrap lumber.  In any event, if the container has been used for planting before it should be sterilized before reusing it.  Because of this, you should be cautious when reusing wooden trays as they are hard to sterilize.  Sterilization can be done by washing the trays in hot soapy water, soaking them briefly in a mild bleach solution, then rinsing thoroughly. Most seed-starters will plant in a flat tray and then transplant the seedlings into individual pots or cells when they have one or two sets of true leaves.  You also can seed in individual containers or cells to avoid transplanting.  This is desirable for some plants that do not like to be transplanted such as the cucurbit family; melons, squash, and cucumbers.

Next – what sort of environment do you need? Almost all flowers and vegetables like a germination temperature of  about 70 degrees and a growing temperature of somewhat less than that. Some seeds need light in order to germinate and others don’t.  Usually those seeds that have a very shallow planting depth are those that require light.  Ordinary indoor temperatures will be fine for growing but you need to find a little warmer spot for germination. Next to a baseboard heater or near a hot air heating vent will do, but you have to be very careful about soil moisture. Add water slowly to the seeding mixture until it is moist but not soggy.  The mixture should not clump together when you squeeze a bit of it in your hand. Then add the seeds being careful to observe the recommended planting depth. Watering the seeded containers is best done by placing the container in a flat tray and filling the tray with one to two inches of water.  The planting mixture in the seeded containers can then wick up the water through the drainage holes in the bottom.  When you can see and feel moisture at the top of the seeded containers, they are ready.  Make sure you label your containers and don’t let them dry out.

All young plants need plenty of light to grow so unless you have a heated greenhouse, you need to provide a light source for your young plants.  A fluorescent light fixture is fine and you can use ordinary fluorescent tubes in it, although I would not buy the “cool white” tubes for plants.  Specialized “full spectrum” tubes are expensive and really not necessary for starting plants, however you might consider them if you are planning to grow plants to maturity indoors. Keep the lamps very close to the tops of the plants as they grow. Don’t use incandescent lights as they put out too much heat and will burn the tops of your plants.

Does talking to your plants help?  It has been shown that vibration helps a plant develop a stronger stalk so perhaps shouting at them would be better.  Seriously, as they are growing on, brushing the tops of the plants gently with your hand occasionally will result in a stronger plant.  Very tall spindly stalks result from a light source which is not adequate; too little light, or too far from the plants.

One caution – if you have cats you probably will need to situate your plant starting spot where the cats do not have access.  Cats love to eat tender young plants and use starting mix as a litter box.  Been there; done that.